Currently matchers (SiteAccess and View) can be referenced by their FQCN service name with '@'. Built-in Matchers are namespace-based, which means that as long as matcher FQCN matches Core namespace, the short name can be used. This is a huge architecture and maintenance issue. Domain level element (Matcher) is mixed here with language specification (namespace).

We should introduce named Matchers (e.g. call it Identifier) so they can be referenced in configuration. Core/Built-in should consume the same SPI for that.